How would you know how much water to use?

I found out that I have to water my plants every three days. But how much should I water them? I'm using 5 gallon pots. How do you know how much to water?
I water them about 1 quart (1 liter) and the drained water is about 1/2 quart (500 mil liter).
Is that good enough? too much or too little?
Thanks

Could get a moisture meter, but it depends on plant size, lighting, and soil type. Since your pots have drainage ports that should help some. Personally I just go by feel/look of soil and try to keep it somewhat damp but not to soaked. Probably want a better answer then that though haha.

I water comes out the bottom of the pot, they've had enough. Depends on the size of the plants too.

Kinda depends on how your soil is, the soil/perlite ratio, what kind of soil, etc... But if you're putting in a quart and getting half of it, sounds like it drains fine, you'd be amazed at the margin of error mother nature gives you. But your first sentence is how it goes. It's nothing someone can just straight up tell you, but you'll figure it out on your own soon enough.

I grow in soil and the way I do it is to stick my finger down about two inches or so and if it feels dry I give it some water. Usually until it starts to run out the drain holes.

your in 5gal pots and the soil will only hold half a litre? Whats the size of the plant? Veg or flower? Sounds to me like your soil has really crap water retention! I use 10ltr pots (2.5gal) half the size of yours and my soil will hold at least 3ltrs of water, and im watering every 4-5days in full flower the time when water uptake is at its peak! In 5gal pots u should be able to go 7days at least unless uv got some 8ft monsters in them, theres no set quota as to how much water to give, u need to get used to the weight of wet and dry pots and this plus using yr finger to test will tell u when to water, some soils when they dry out can be quite hard to re-wet, so what u wana do is use a water can with a fine rose head and just water the surface of the soil a little, wait 5mins then soak the soil till u get some run-off, wait half an hour and by this time the soil should have re-absorbed the run off back into the pot, water again till run off then yr done, sounds to me like yr just dumping water on dry soil which will make it just run straight thru the soil and down the sides of the pot before it gets a chance to be absorbed, or yr soil has no water retention value to it

Good point Londoner, I failed to mention that you should add water very slowly. plus rep for you.

yes m8 watering slowly in stages is the key to good watering, just dumping water onto the soil from a jug, cup bucket or even just the bare open end of a water can not only doesnt give the soil a chance to absorb the water, but will also compact the soil down very quickly after 3or4 waterings or so, thus making it retain less water and also reduce airation of the soil, and we all know roots have a hard time growing thru compacted soils. Little birdy tells me that 20% coco coir mixed with soil before planting does wonders for water retention and adds airation, also coco is believed to naturally harbour trichoderma harzianum, a friendly fungus that works in harmony with yr plant protecting it from pathogens like root rot, botrytis, oxysporum and its now even believed to fight the deadly fusarium!

and i wouldnt bother with a moisture meter, waste of money, they are meant for general gardening where wet/dry standards are totally different to growing mj, iv found when they say the soil is very dry, it is infact still moist enough for another couple of days, learn to judge the weight of yr pots when wet and dry, obviously this will change as the plants grow and put on weight during bloom, but keep doing this and u'l soon get used to how much it should weigh throughout the growth of the plants, this way will give u far more experience and teach u alot more than relying on an inaccurate meter.

The plants are only two to three weeks old and transplanted last week.

ok 2-3 week old plants need very little water, in 5gal pots u should be able to go more than a week between waterings, as an example my 3-4 weeks olds are in 1gal pots nearly ready to be potted up to bigger pots, ranging from 10-14" tall are being watered every 7-8 days and they could go a bit longer, yr at risk of doing permenant overwatering damage to yr plants, water them as i said, a good soaking in a couple of stages, guage the weight of the heavy watered pot, then wait til pot is very light and the soil feels dry to yr finger 2-3" down the pot, a good way to get used to the weight of pots is fill two pots with soil soak one and leave the other to completly dry out bone dry and lift each one a few times every day, u'l soon get what i mean. What soil and lights are you using?

buy a moisture tester or let ur plants tell u when they need watering. Get to know them it will help if u have problems.

AquafinaOrbit said:

Could get a moisture meter, but it depends on plant size, lighting, and soil type. Since your pots have drainage ports that should help some. Personally I just go by feel/look of soil and try to keep it somewhat damp but not to soaked. Probably want a better answer then that though haha.

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A moisture meter? It does not sound like a bad investment........

Depending on the size of the pot, Little pot then a little water but the bigger the pot is the more water it consumes.